Lubricating compositions



United States Patent 3,030,304 LUBRICATING COMPOSITIDNS John Scotchford Elliott and Eric Descarnp Edwards, London, England, assiguors to Castro] Limited, a British company No Drawing. Filed Feb. 6, 1959, Ser. No. 791,532 Claims priority, application Great Britain Feb. 11, 1958 6 Claims. (Cl. 252-461) This invention is for improvements in or relating to lubricating compositions and is particularly concerned with lubricating compositions having extreme pressure properties especially suitable for the lubrication of hypoid gears, which compositions will operate under conditions of low speed and high torque as well as under conditions of high speed and high load.

It is well known that under certain conditions, eg' for the lubrication of hypoid gears, it is necessary to employ lubricants containing chemical compounds capable of reacting with metals at high temperatures and under high pressures to form films (e.g. of iron sulphide, iron chloride or iron oxide) which prevent seizure and welding of the metal surfaces. A variety of organic compounds have been suggested for this purpose, including sulphur compounds of various types and containing sulphur in varying degrees of activity. It has generally been found advantageous to use these sulphur compounds in conjunction with lead soaps or organic halogen compounds, or both. It is now recognised that many such lubricants, which behave perfectly satisfactorily under normal operating conditions and even under high loads at high speed, are not satisfactory under conditions of high torque and low speed, e.g. for lubricating rear axles of vehicles operating in mountainous terrain. Under these conditions, certain lubricants, e.g. those containing lead soaps or sulphur in active form, tend to cause high rates of wear or, in some cases, rippling or ridging of the gear teeth, and to promote the rusting of ferrous metal parts in presence of condensed moisture.

' On the other hand lubricants which perform well under conditions of low torque and high speed do not necessarily possess adequate load-carrying capacity under high-speed conditions and particularly under conditions of shock loading. In fact the two requirements have been for some time regarded as being conflicting and U.S. Army specification MILL2105, to which most commonly used hypoid rear axle oils have conformed for several years past, represents a compromise.

The practice among motor manufacturers for some time past has been to use lubricants having better E.P. properties under high-speed conditions than the conventional MIL- L-2l05 oils for factory fills for passenger cars. After running-in the gears for a certain period on these oils, which generally contain active sulphur and sometimes also lead soaps, the rear-axle may be drained and filled with MIL-L-ZIOS oil. Some of these oils, particularly those containing lead soaps, while providing adequate protection of the gears against scuffing, have been found to give rise to an undesirable amount of wear in antifriction bearings resulting in loss of pre-load with consequent deterioration of the gear and development of noise and other troubles. Furthermore, it is an obvious disadvantage to have diiferent rear axle oils for factory fills for passenger cars and trucks, since confusion may occur and breakdown of heavily-loaded truck axles might take place under low-speed high-torque conditions if lubricated with an oil of the wrong type.

Recent improvements in engine designs have led to increased power output and this, combined with the tendency to increase the hypoid pinion offset, has brought about a very considerable increase in the severity of the operating conditions of the gears of passenger cars. The

loading on truck axles has also increased and the high speeds at which many vehicles, particularly military vehicles, operate combined with the heavy loads carried have exposed the limitations of MIL-L-2l05 oils both under high-speed conditions of operation and under lowspeed high torque conditions.

The need for a universal hypoid axle lubricant suitable for factory fills for passenger cars and at the same time having superior extreme pressure properties to MIL- L-2105 oils both under high-speed and low-speed hightorque conditions has for some time been appreciated, and new full-scale axle test procedures have been devised for the purpose of evaluating such lubricants.

The increased performance required of such lubricants under low-speed high-torque conditions may readily be appreciated by comparing the standard CRC-L-2O test of U.S. military specification MIL-L-2l05 with the new CRC-L-37 test. Both tests are carried out using /1, ton Army truck hypoid rear axle carriers, generally similar in design, the essential differences in test procedure being summarised in the following table:

Speed (ring-gear) r.p.m 62 Soil. Ring-gear torque, in-lbs. 32,311-. 41,800. Oil temperature Cycling between 275=|=3 F. (con- 200 and 250 F. stant). Duration, hours 30 24. Runningdn procedure Approx. 20 mms. None.

In the LS7 test prior, to the low-speed high-torque test, a high speed low torque test is carried out for minutes at 440:5 r.p.m. and with a ring-gear torque of 9460: in-lb., the maximum oil temperature permitted without cooling being 300 F. It will readily be seen that the new test is in several respects, particularly as regards loading and oil temperature, considerably more severe than the old.

For evaluating performance under high-speed conditions a new test, CRC-L-42, has been developed which is likewise more severe than the old CRC-Ll9 high-speed axle test of MIL-L-ZIOS specification. Additionally various severe shock-loading tests have been evolved such as the Chevrolet Bump test and the Buick 10A test.

In addition to satisfying the requirements of these tests, a universal hypoid axle lubricant must be relatively noncorrosive to cuprous metals at high operating temperatures and must provide adequate resistance to the corrosion of ferrous metals in the presence of water.

We have now found that by employing certain com binations of separate additives in a lubricating oil, effective lubrication of hypoid gears under both high-speed and low-speed high-torque conditions can be obtained, said combination of additives being stable up to 275 F. or even higher. The three separate additives are:

(a) A chlorine-bearing hydrocarbon having a boiling point or decomposition temperature not less than C.

(b) An aliphatic or aryl-substituted aliphatic disulphide which may or may not contain chlorine substantially nonreactive to iron or copper at 100 0., and

(c) A dialkyl phosphite.

Alternatively, additive a can be omitted from the composition provided that additive b contains chlorine-substituted aliphatic radicals to provide the chlorine content necessary to confer on the composition the desired extreme pressure properties.

The provision of both chlorine and sulphur by additives a and b is necessary to provide adequate loading under high-speed and shock loading conditions. These additives are well known and have previously been used in combination, e.g. in compositions containing phosphosulphurised esters and fatty oils. However, many such compositions have been found to be unsatisfactory at temperatures of 275 F. and above and to result in extensive sludging due to the thermal instability of these latter materials.

The addition of additive c enables the lubricant to operate satisfactorily under conditions of low-speed and high-torque and this addition not only does not interfere with the action of additives a and b but actually enhances it, especially under conditions of shock loading.

According to the present invention there is provided a lubricating composition comprising a mineral lubricating oil having incorporated therein additives a, b and c, to confer extreme pressure properties on the composition a being a chlorine bearing hydrocarbon having a boiling point or decomposition temperature not less than 160 C.,' b being an aliphatic or aryl-substituted aliphatic disulphide which may or may not contain chlorine and c being a dialkyl phosphite or alternatively a minor proportion of additives b and only when b is a chlorinated aliphatic disulphide, the additive b being substantially non-reactive to iron or copper at 100 C.

A suitable chlorinated aliphatic disulphide b may be prepared by reacting a chlorinated kerosine or a chlorinated parafiin wax with an alkali metal disulphide in such amount as to replace a minor proportion of the chlorine atoms by disulphide groups.

When additive a is present it is preferably a compound containing not less than about 30% by weight of chlorine, this being preferably not directly attached to an aromatic nucleus.

Examples of additive a are:

It is to be understood that when additive a is present in the composition the alkyl or aryl-substituted alkyl groups may contain halogen substituents. A suitable chlorinated disulphide which can be employed in compositions according to the present invention is, for example, dichlordibenzyl disulphide.

Examples of additive c are:

Diethyl phosphite, Di-isopropyl phosphite, Di-n-butyl phosphite, Dioctyl phosphite, Dilauryl phosphite.

These phosphites have the formula:

where R and R are the same or different alkyl groups. Preferably R and R have at least three carbon atoms.

Additives a, b and c or additives b and c are preferably employed in an amount to provide at least 0.5% by weight of chlorine, 0.3% by weight of sulphur, and 0.1% by weight of phosphorus, respectively in the lubricant. More preferably the additives are present in an amount to provide between 1 and. 4 percent by weight of chlorine, be-

tween 0.5 and 2 percent by weight of sulphur and between 0.15 and 0.5 percent by weight of phosphorus.

Lubricating compositions according to the present invention while giving satisfactory lubrication of hypoid gears under both high-speed and low-speed high-torque conditions, do not provide sufiicient protection of the gears and axle housing etc. in the presence of moisture. Inhibition of corrosion under these conditions, which is believed to be accelerated by the liberation of hydrogen chloride or chlorine from a, or b (if b contains chlorine), during the actual operation of the gears, is quite a problem and requires special additives which are compatible with the other additives present and which do not interfere with their functions.

In a preferred form of the present invention there is included in the lubricating composition a further compound, additive d, an oil-soluble basic alkaline earth metal sulphonate Which may or may not be neutralised with a weak acid, e.g. carbon dioxide. We have found that compounds a are very effective corrosion inhibitors being greatly superior to the neutral sulphonates which have but little anti-corrosive action in combination with additives a, b and c.

Additive d is preferably employed in an amount of at least 0.05% and more preferably in an amount of from 0.1 to 0.5%, by weight on the weight of the total composition. Examples of additive d are:

Basic barium petroleum sulphonate,

Basic calcium petroleum sulphonate,

Basic strontium petroleum sulphonate,

Basic barium dinonyl naphthalene sulphonate, and Basic barium didodecyl or octadecyl benzene sulphonate.

Any of these compounds may be neutralized wholly or in part with CO to give the corresponding carbonate complex.

There may also be included in the compositions of the present invention antioxidants of which oil-soluble metal dialkyl phosphorodithioates are preferred e.g. zinc dihexyl phosphorodithioate or one of the compounds disclosed in our United States patent application No. 718,496 now abandoned. The antioxidant may be present in an amount of from 0.1 to 1.0% by weight on the weight of the composition.

As additional corrosion inhibitors there may be present aldimines or ketimines obtained by the action of an aldehyde or a ketone on a basic water-solubleprimary or secondary mono-amine as described in British patent specification No. 588,864 e.g. dimorpholinyl phenyl methane.

We have further found that the lubricants of the present invention may be improved still further with respect to resistance to breakdown under shock loading conditions by the incorporation in the composition of quite a small amount of an aromatic nitro-compound, preferably a nitrophenol. Thus, for example, we may employ from 0.02 to 0.5 percent of m-dinitrobenzene, u-nitronaphthalene, nitro-p-dichlorbenzene, o-nitrophenol or 2:4 dinitrophenol.

Other additives may also be present, for example, foam inhibitors, pour point depressants and viscosity index improvers.

Following is a description by way of example of two lubricating compositions made in accordance with the present invention (the percentages being on a weight basis).

' EXAMPLE 1 Anniversal hypoid gear lubricant, conforming to S.A.E. (Society of Automotive Engineers) gear oil classification grade 90, was compounded consisting of:

58.0% mineral oil A 25.0% mineral oil B 8.0% mineral oil C 3.7% chlorinated paraffin wax-(approx. 40% Cl) f 2.8% dibenzyl disulphide 1.4% di-isopropyl phosphite 0.5% mineral oil concentrate containing about 85% of zinc salts prepared from mixed dihexyl and di-isopropyl phosphorodithioic acids in 70:30 ratio (antioxidant A) 0.5% mineral oil concentrate containing about 40% of basic calcium petroleum sulphonate (alkalinity of concentrate about 15 mgs. KOH per grn.) (Corrosion inhibitor A).

0.1% polymethacrylate type pour point depressant Mineral oil A was a solvent-refined brightstock of viscosity about 600 seconds Redwood 1 at 140 F., mineral oil B was a solvent-refined mineral oil of viscosity about 150 seconds Redwood 1 at 140 F. and mineral oil C was a solvent-refined mineral oil of viscosity about 65 seconds Redwood l at 140 F. The chlorine, sulphur and phosphorus content of this example is 1.7 percent, 0.86 percent and 0.32 percent, respectively.

EXAMPLE 2 Another S.A.E. 90 hypoid gear lubricant was compounded consisting of:

Mineral oil D Was a conventionally refined brightstock of viscosity about 750 seconds Redwood 1 at 140 F. and mineral oil E was an oil of viscosity about 65 seconds Redwood 1 at 140 F. and viscosity index about 60. The chlorine, sulphur and phosphorus content of this example is 2.6 percent, 0.77 percent and 0.29 percent, respectively.

Further examples were prepared of S.A.E. 90 hypoid gear oils in accordance with the present invention, the mineral oil blends employed being similar to those described'iu Examples 1 or 2, the amounts of additives incorporated in the composition being as follows:

EXAMPLE 3 4.0% chlorinated paraffin wax (approx. 40% Cl) 3.0% dibenzyl disulphide 1.0% di-isopropyl phosphite 0.5% antioxidant A 0.5% mineral oil concentrate containing about 45 of basic barium petroleum sulphonate (alkalinity about 40 mgs. KOH per grm.). Corrosion inhibitor C.)

The chlorine, sulphur and phosphorus content of this example is 1.7 percent, 0.86 percent, and 0.23 percent respectively.

EXAMPLE 4 4.0% chlorinated parafiin wax (approx. 40% CI) 3.0% dibenzyl disulphide 1.0% di-isopropyl phosphite 0.2% dimorpholinyl phenyl methane (corrosion inhibitor D) The chlorine, sulphur and phosphorus content of this example is 1.7 percent, 0.78 percent and 0.19 percent, re-

spectively.

EXAMPLE 5 2.7% chlorinated parafiin wax (approx. 40% Cl) 3.3 I monochlor-dibenzyl disulphide 1.4% di-isopropyl phosphite 5 0.5% antioxidant A 0.5% corrosion inhibitor A The chlorine, sulphur and phosphorus content of this example is 1.5 percent, 0.81 percent and 0.28 percent, respectively.

EXAMPLE 6 2.5 chlorinated paralfin wax (approx. 40% Cl) 3.0% dichlor-dibenzyl disulphide 1.0% di-isopropyl phosphite 0.5 antioxidant A The chlorine, sulphur and phosphorus content of this example is 1.7 percent, 0.83 percent and 0.21 percent,

respectively.

EXAMPLE 7 2.0% hexachlorethane 2.0% ii-tertiary butyl disulphide 1.5% diethyl phosphite 0.5% mineral oil concentrate containing about of zinc salts prepared from mixed dicapryl and di-isopropyl phosphcrodithioic acids (antioxidant C) 0.2% corrosion inhibitor C The chlorine, sulphur and phosphorus content of this example is 1.8 percent, 0.80 percent and 0.38 percent,

respectively.

EXAMPLE 8 0.5% basic barium dodecyl benzene sulphonate (corrosion inhibitor E) 2.0% mineral oil concentrate containing about 45% of mixed barium phosphorodithioates of C -C a-lco'hols (antioxidant D) The chlorine, sulphur and phosphorus content of this example is 1.93 percent, 0.74 percent and 0.40 percent, respectively.

EXAMPLE 10 4.0% chlorinated mixture of diand polyphenyls (65% 3.0% dibenzyl disulphide 1.5% di-isopropyl phosphite 0.5 antioxidant A 0.5% corrosion inhibitor A The chlorine, sulphur and phosphorus content of this example is 2.6 percent, 0.86 percent and 0.32 percent, respectively.

. EXAMPLE 11 3.7% chlorinated parafiin wax (40% Cl) 3.2% monochlor dibenzyl disulphide 1.4% di-isopropyl phosphite 0.5 antioxidant A 0.5% corrosion inhibitor A 0.1% 2,4 dinitrophenol The chlorine, sulphur and phosphorus content of this example is 1.9 percent, 0.81 percent and 0.30 percent, respectively.

In order to evaluate the performance of various oils as lubricants for hypoid gears operating under condi-- tions of low-speed and high-torque, tests were carried out on the Well-known Society of Automotive Engineers '2? (S.A.E.) Machine, modified in a similar manner to that described by McKee, Swindells, White and Mountjoy in the paper presented at S.A.E. National Fuels and Lubricants Meeting, St. Louis, Missouri, November 1949.

In order to obtain a measure of the usefulness of the compositions of the present invention as hypoid gear lubricants under high-speed and shock-loading conditions, tests were carried out on the well-known Almen The machine was run at constant load for periods up Extreme Pressure Lubricant tester, described by West in to 12 hours with a main shaft speed of 500 r.p.m. and the Journal of the Institute of Petroleum, vol. 32, page rubbing ratio 3.421, the oil being continuously circulated 220 (1946). by means of a pump from a reservoir provided with A novel test procedure was used on the Almen machine heating and cooling coils so that the oil could be maindesigned to simulate conditions of shock loading. After tained at a constant temperature (275' F.). The test starting the machine and loading up to 4000 lbs/sq. inch cups were given a preliminary run-in for minutes at in the standard manner, the pan and Weights were lifted 50 lb. load. manually a distance of 4 inches and suddenly released,

The results of tests on selected compositions fornmthree successive bumps being performed at 5 second lated in accordance with the present invention are sum intervals at each load. If no seizure took place, the marized in Table I, together with test results on certain 15 procedure was repeated at successive load increments reference oils. The S.A.E. machine test results were of 1000 lbs/sq. inch until the pin seized. Tests were assessed on the basis of (1) total weight loss of thetest carried out in duplicate or triplicate. cups (2) surface finish of test cups and (3) sludging of The'results of Almen shock tests are summarized in the oil. Table II. a

Table l [011 temperature, 275 F. Load, 250 lbs.)

Test Total Test Lubricant duration ring Condition of test cups Condition of oil No. (hours) weight loss (mgs) 1 Reference oilA g }Smoothing (top), burnishing (bottom)-.. Heavy sludging-black deposits 2 Reference 011 B 3 1 888 }Heavy wear and ridging Satisfactory. 3 Reference oil 0 2% 1, 490 Heavy wear, ridglng and scoring Do. 4 Composition of Example 1-.-- 12 37 Burnishlng (top), slight ridging (bottom) Do. 5 Composition of Example 2.-.- 4 118 Deep ridging in centres of rings Do. 0 Composition of Example 3 12 18 Slight ridging and rippling (top), burnishing (bot- Do.

om 7 Composition of Example 4.-" 12 83 Similar to Test No. 4 Do. 8 Composition of Example 5 12 105 Smoothing (top), burnishing (bottom). Do. 9 Composition of Example 6 12 60 Similar to Test No. 4 Do. 10 Composition of Example 7 5 Light ridging (both)-- Moderate sludging. 11 Composition of Example 9.-.- 5 51 Burnishiug (both) Do. 12 Composition of Example 10"- 5 57 0 Do. 13---- Composition of Example 1 4 3,150 Hcavyridging andrippling, metal removal at edges. Do.

Without di-isopropyl phosp 1 9. 14-.-" Composition of Example 11 5 38 Satisfactory (top), slight burnishing (bottom) Do.

NOTE-The term "satisfactory in the final column implies no more than slight sludging of the oil.

Referring to Table 1, reference oil A was an S.A.E. Table II 90 hypoid gear oil containing the recommended propor- ALMEN .SHOCK TESTS tion of a. commercially available additive and met the requirements of US. specification MIL-L-2105. This Almen Shock t'estresults oil therefore passed the L-20 low-speed high-torque axle T t test. It was known to fail the new L-37 test, however, Lubricant Failure Numl Failure due to sludging. This was confirmed by the modified load gm of oadi guerof S.A.E. Machine test. 5; f4 amps umps Reference oils B and C were S.A.E. 90 hypoid gear oils containing two diiferent commecidally availalgle ladtilll- Reference on A" Ole g b igfi from tives in t e proportions recommen e to pass ot t e A100 ,0 3. sq. 111.

16..- Rf L-37 and L-42 tests. These oils, though satisfactory as 3353333 83 3 3 388 g 83?, 3 regards sludging and deposit-formation, gave rise to very c s 15000 2 19-.. Com osit1onotExomle1 9,000 3 10,000 1 hlgh wear in the S.A.E. test, whereas the compositions 20m comgomn E g1 2 9,000 2 10,000 1 f 1 21--. Compositional Example 5..- 10,000 2 11,000 1 of the present invention gave relatively ow wear even 22 compositionomxample7m 15000 (1) 15000 (I) under the very severe conditions of this test and, 111 gen- Composition ofExample 11,000 1 11,000 3 I 24--- CompositionofExamplcQ-.. 13,000 3 14,000 1 eral, produced no more a shght increase in surface 25. oompositionomxample 10" 8'00) 1 7,000 3 roughness. The composition of Example I successfully 2s CompositionofExample 11.. 1'5,000 15,0o0 passed the L 37 l test. 27--- Compositronpf Example 1 8,000 1 9,000 1 Without di-isopropyl phos- Ornrssron of the dialkyl phosphite from the composiphite. 1

tion of Example 1 (test 13) led to severe surface dam- PP P Examille 1 7,000 2 81000 1 witnoutdibenzyl disulage of the rings, this being illustrative of the behaviour phide. u I

pounds only. Another such lubricant (reference oil D) afliin wax.

containing active sulphur and chlorine and very effective under high-speed operating conditions resulted in a loss No a ure.

of 590 even at 200 1b 1 d d 225 F, il t It will be .seen from Table II that reference oils B and perature, coupled with ridging, rippling and pitti f C containing additives present 1n suflicient proportions to the rings. Although various phosphorus-containing additives are eifective to a greater or lesser extent in improving the performance of such oils under low-speed high torque operating conditions, we have found the dialkyl phosphites to be outstandingly effective.

pass the L-42 test, withstood a substantially greater load than the MIL-D2105 lubricant, reference oil A, which would fail the L-42 test. Reference oil D withstood a high load, but this oil was of the active sulphur type, suitable for factory fills. The results of the tests. on the lubricants according to the present invention show that the lubricants range in effectiveness for the most part between reference oils B and C and in some cases were even better than oil B. Omission of the dialkyl phosphite from the composition of Example 1, a typical lubricant of the present invention, led to a significant reduction in its ability to withstand shock loading conditions, an even greater reduction in load carrying capacity being obtained when either the sulphur-containing compound or the chlorine-containing compound is omitted. The poorest result among the lubricants of the present invention was given by the composition of Example 10, in which the chlorine compound contained chlorine attached to an aromatic nucleus.

In order to investigate the anti-corrosive properties of the lubricants of the present invention, Chrysler-Almen corrosion tests were carried out, this test being designed to give an indication of the behaviour of a hypoid gear oil in service or in the Moisture Corrosion Axle test of United States Specification M1L-L-2105. In this test procedure the Almen machine was started and loaded up to 4000 lbs/sq. inch in the standard manner and thereafter run for 25 minutes under this load. The test pieces were then removed, placed in Gooch crucibles standing on watch glasses and allowed to drain in an oven at 180 F. for 30 minutes. The crucibles were then removed and allowed to stand for 24 hours in a desiccator over water and examined for signs of rusting. The results obtained are summarized in Table III.

Table III CHRYSLER-ALMEN CORROSION 'rns'rs Corrosion of Test Lubricant No.

Pin Bushes 30 Reference oil A None 1 Slight. 31-... Referemce oil IL- Fairly heavy Fairly heavy. 32 Reference oil C N slight. 33.-.- Composition of Example 1 d 34- Composition of Example 2. Very slight. 35 Composition of Example 3. d 36".- Composition of Example 5. One or two Slight.

37- Composition of Example 8. Do. 38 Composition of Example None. 39...- Composition of Example 11.-- Do. 40 Composition of Example 1 Heavy.

Xithout Corrosion Inhibitor 41. Composition of Example 8 D0.

Xithout Corrosion Inhibitor 42-.-. Composition of Example 1 Fairly heavy.

with 0.2% neutral calcium petroleum sulphonate in place of Corrosion Inhibitor 43..-. Composition of Example 1 None Very slight.

with 0.125% basic barium octadecyl benzene sulphonnte in place of Corrosion Inhibitor A.

1 Heavy wear.

The effectiveness of the corrosion inhibitors at will be seen from the foregoing Table III by comparing tests 33 and 43 with test 40 and test 37 with test 41. The neutral calcium petroleum sulphonate in test 42 was relatively ineffective. It should be pointed out, however, that of the chlorinated hydrocarbons which may be employed as additive a in the present invention some, e.g. hexachlorethane, are more prone to give rise to corrosion than others and may therefore require larger amounts of corrosion inhibitor d to provide adequate protection.

We claim:

1. A lubricating composition consisting essentially of a major proportion of mineral oil having incorporated therein a minor proportion of a chlorine and sulphur-containing additive to provide in the composition between 0.5 and 4% by weight of chlorine and between 0.3 and 2% by weight of sulphur together with a minor proportion of a dialkyl phosphite having a total number of from 4 to 24 carbon atoms in the alkyl groups to provide between 0.1 and 0.5% by weight of phosphorus, to thereby confer on the composition extreme pressure properties; said chlorine and sulphur containing-additive being selected from the group consisting of (1) a chlorinated aliphatic disulphide and (2) a combination of a chlorine-bearing sulphur-free hydrocarbon having a boiling point and decomposition temperature not less than 160 C. With a sulphur-containing compound selected from the group consisting of aliphatic disulphides, aryl-substituted aliphatic disulphides, and chlorinated aryl-substituted aliphatic disulphides, which sulphur-containing compound is substantially non-reactive to iron and copper at 100 C.

2. A lubricating composition as recited in claim 1 wherein chlorine and sulphur are provided by a combination of a chlorine-bearing hydrocarbon having a boiling point and decomposition temperature not less than 160 C. and a sulphur-containing compound selected from the group consisting of aliphatic disulphides, aryl-substituted aliphatic disulphides, and chlorinated aryl-substituted aliphatic disulphides.

3. A lubricating composition as recited in claim 1 wherein chlorine is provided by a chlorine-bearing hydrocarbon selected from the group consisting of chlorinated paraffin Wax, a chlorinated kerosene, hexachlorethane, benzene hexachloride, a chlorinated terpene, a chlorinated indene, dichlordiphenyltrichlorethane and a chlorinated di- References Cited in the file of this patent UNITED STATES PATENTS 2,066,173 Calcott et a1 Dec. 29, 1936 2,134,436 Cantrell et a1. Oct. 25, 1938 2,208,161 Prutton et al. July 16, 1940 2,294,817 Van Dijck Sept. 1, 1942 2,364,284 Freuler Dec. 5, 1944 2,711,396 Dorinson June 21, 1955 FORElGN PATENTS 455,494 Canada Mar. 29, 1949 

1. A LUBRICATING COMPOSITION CONSITING ESSENTIALLY OF A MAJOR PROPORTION OF MINERAL OIL HAVING INCORPORATED THEREIN A MINOR PROPORTION OF A CHLORINE AND SULPHUR-CONTAINING ADDITIVE TO PROVIDE IN THE COMPOSITION BETWEEN 0.5 AND 4% BY WEIGHT OF CLORINE AND BETWEEN 0.3 AND 2% BY WEIGHT OF SULPHUR TOGETHER WITH A MINOR PROPORTION OF A DIALKYL PHOSPHITE HAVING A TOTAL AMOUNT OF FROM 4 TO 24 CARBON ATOMS IN THE ALKYL GROUP TO PROVIDE BETWEEN 0.1 AND 0.5% BY WEIGHT OF PHOSPHORUS, TO THEREBY CONFER ON THE COMPOSITION EXTREME PRESSURE PROPERTIES; SAID CHLORINE AND SULPHUR CONTAINING-ADDITIVE BEING SELECTED FROM THE GROUP CONSISTING OF (1) A CHLORINATED ALIPHATIC DISULPHIDE AND (2) A COMBINATION OF A CHLORINE-BEARING SULPHUR-FREE HYDROCARBON HAVING A BOILING POINT AND DECOMPOSITION TEMPERATURE NOT LESS THAN 160*C. WITH A SULPHUR-CONTAINING COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALIPHATIC DISULPHIDES, ARYL-SUBSTITUTED ALIPHATIC DISULPHIDES, AND CHLORINATED ARYL-SUBSTITUTED ALKIPHATIC DISULPHIDES, WHICH SULPHUR-CONTAINING COMPOUND IS SUBSTANTIALLY NON-REACTIVE TO IRON AND COPPER AT 100*C. 